Suppressed a possible E_WARNING PHP error in CDbConnection::createPdoIns...

...tance() which might occured when the mysqlnd PDO driver was in use

Summary: The native mysql PDO driver may trigger a E_WARNING which will just abort the script and is unlike a proper CDbException not catchable.

Before fix:

    PHP warning
    PDO::__construct() [<a href='pdo.--construct'>pdo.--construct</a>]: [2002] Es konnte keine Verbindung hergestellt werden, da der Zielcomputer die Verbindung verweigerte. (trying to connect via tcp://localhost:3306)

After fix:

    CDbException
    CDbConnection failed to open the DB connection: SQLSTATE[HY000] [2002] Es konnte keine Verbindung hergestellt werden, da der Zielcomputer die Verbindung verweigerte.

Related links:

https://bugs.php.net/bug.php?id=53185
http://www.yiiframework.com/forum/index.php/topic/31268-handle-stopped-database/